Elon Musk has been trying to create some synergy between his seemingly unrelated companies, Tesla and SpaceX.

The CEO might have found one way to help both companies: combining their efforts to create new materials that could be used both on electric vehicles and renewable energy products on Earth, as well as in spacecraft and rockets in space.

Tesla and SpaceX have been building material engineering teams to develop new advanced materials for their respective products.

The teams are so interlinked that Tesla recruiters referred to them as a “SpaceX/Tesla Materials Engineering organization” – apparently “mistakenly”, according to Tesla.

It started just over two years ago when we reported in an exclusive report that Musk hired Apple’s alloy expert Charles Kuehmann to lead materials engineering at both of his companies simultaneously.

Kuehmann earned a PhD in Materials Science & Engineering from Northwestern University in 1994 and co-founded QuesTek two years later with four other colleagues affiliated with Northwestern University to commercialize the work of his mentor and pioneer in the field of computational materials design; Prof. Gregory B. Olson, who has been called the “father of materials design” by the American Academy of Arts and Sciences.

At QuesTek, he went on to successfully develop and commercialize not only several new materials engineering tools and processes, but also numerous new alloys based on a number of different elements including Al, Co, Cu, Fe, Mo, Ni, Nb, Ti, and W.

The company was later acquired by Apple and Kuehmann went on the lead the development of new aluminum alloys for the Cupertino company’s products.

Kuehmann made the jump to Tesla and SpaceX in late 2015 and he has now helped build significant teams of dozen of material engineers at both companies.

The exec is not alone with a foot at each company. Computational materials scientist Maarten De Jong also lists his position as a materials engineer at both Tesla and SpaceX on LinkedIn.

Tesla is currently still looking to grow its advanced materials team with new metallurgists and materials engineers.

A recent listing for a senior metallurgist job opening at Tesla even mentioned that the role was part of “the SpaceX/Tesla Materials Engineering organization”:

“This role will report to the Manager of Metals, Ceramics and Glasses in Tesla Materials & Processes Engineering, which is a part of the SpaceX/Tesla Materials Engineering organization.”

We reached out to Tesla for this listing and they are downplaying the partnership. The listing has since been removed and Tesla told Electrek that the collaboration between the two companies is not as “formal” as this statement would suggest.

But Tesla did confirm that on top of sharing a VP of materials engineering, the materials teams of both Tesla and SpaceX hold joint meetings and collaborate to solve issues with material development.

The companies worked together to build a database of materials to help with their respective material programs.

While they are considered “sister companies”, they are completely separate entities and it can be confusing to have them working together on what could lead to the development of new alloys and important intellectual property.

Tesla says that while they developed some software together, the actual data and information from the materials teams are unique and proprietary to each company.

Musk often talks about the difficulties involved in running two companies, but he also acknowledges some advantages of being active in two different industries. SpaceX aims to dramatically reduce the cost of rockets and if there’s an industry who mastered the art of making complex vehicles cheap, it’s certainly the automotive industry.

On the other hand, Tesla has benefited from SpaceX’s expertise of high-tech manufacturing techniques such as stir welding, a technique SpaceX uses to join large sheets of metal like the ones used for the aluminum tank of their rockets.

Now they are also sharing knowledge of materials engineering to create new alloys for their respective products.

New aluminum alloys, which is Kuehmann’s expertise, are something that Musk’s companies could make good use of throughout their product lineups.

The Tesla Model S and X are primarily made of aluminum, which proves strong and light, but also suffers from malleability and is expensive to repair. With the Model 3, Tesla used less aluminum and more steel.

Tesla and SpaceX also both use the space-grade superalloy Inconel. In the case of Tesla, the automaker uses inconel for the main pack contactor on its “Ludicrous upgraded” battery packs, while SpaceX uses it to manufacture the SuperDraco engine.